The permissions are correct, users may not add something directly in /var/www/clients/client1/web52/ as thats the web root and this folder has to be owned by root, if it would be owned by the ssh user that you crarted, then he would be able to take over your server and I guess that not what you want. The home directory of a user is /var/www/clients/client1/web52/home/username/ btw.